(a) Field of the Invention
The present invention relates to a side curtain airbag, which prevents passengers from being injured by side windows or car frames at rollover, and an airbag system comprising the same.
(b) Description of the Related Art
Generally, an airbag is the device that protects a driver and passengers. When a car collides head-on at 40 km/h or more, an impact sensor of the airbag reacts to collision and makes a powder explosion. It puts gas into inside of the airbag and makes the airbag expand.
Especially, a side curtain airbag is the airbag installed in a side window or side car frames to prevent passengers from colliding with side windows or car frames at rollover.
In order to minimize the secondary impact to passengers caused by the airbag and get a driver's view, an ordinary airbag installed in the front side of a car interior should expand quickly by an explosive gas and discharge the gas in a short time. For these, the ordinary airbag mostly has a hole for discharging the gas.
However, the side curtain airbag is a device that prevents passengers from being injured by side windows or car frames at rollover. Thus, the side curtain airbag must remain inflated and support passenger's head safely for at least 6 second at rollover. For these, the gas should not excessively leak out from a sewed part and a fabric of the airbag. Thus, the side curtain airbag doesn't have the hole for discharging the gas in general.
In order to prevent discharging excessive gas in the sewed part, U.S. Pat. No. 5,685,347 discloses a preparing method of a OPW (One Piece Woven) airbag that simultaneously weaves upper and lower fabric in a single piece having an inflating part therein with jacquard loom. However, the method needs the jacquard loom with an expensive electronic device and has a difficulty to input patterns for weaving. Moreover, the OPW airbag has another problem that the fabric cannot be used as an airbag fabric in case of only a defect while weaving.
Furthermore, JP Patent Publication NOs. 1992-081342, 1992-197848, and 1991-010946 disclose a process that seals a sewed part by an adhesive tape and so forth after sewing a fabric coated with rubber materials, in order to prevent leakage of the gas from the sewed part in an airbag. However, the method has problems, such as having complicated process and increasing the cost for preparation because of additional sealing process.
Therefore, a study for developing the side curtain airbag, which has an excellent capacity of keeping an internal gas pressure to the extent of protecting passengers safely at rollover, is required. In addition, it is required that the cost for preparation of the side curtain airbag is lowered and the side curtain airbag is efficiently prepared through an ordinary weaving, cutting, and sewing process.